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Voltage level on temperature alert output is inverted(on MCP9600)

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edenNM

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I am able to read temperature accurately using MCP9600. Its a Thermocouple EMF to Temperature Converter.

The MCP9600 digital temperature sensor comes with user-programmable registers which can be used to detect multiple temperature zones. I.e. it can be configured to detect when the Hot junction of a thermocouple reaches(passes) a certain temperature.

The temperature alert limits has user programmable configurations for alert polarity (as either an active-low or active-high) output. In addition, the alerts can detect either a rising or a falling temperature with up to 255°C hysteresis. i configured:-

  • Alert 1 Limit Register as 0x200 ( alert limit = 32degree C)
  • Alert 1 Hystersis Regster as 0x00(alert hysteresis = 0 degree C)
  • Alert 1 Configuration Regster as 0b00001001( normal state, monitor T(h), rising, active low, comparator mode, alert o/p enable).

pic1.PNG

shows the third register. and the expected output was supposed to look like

expected output.PNG.

However, the output remains low from 0-32 degree centigrade and when it passes 32 degreecentigrade, it becomes high. i.e. its inverted

current output(wrong).png

It should have gone from 'high' to 'low' as the temperature increases and reaches 32.

Why is the voltage level reversed?
 

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